Timesheets are mandatory and is a demand from the European Commission for EU projects.
“Employees have to record their time on a daily, weekly, or monthly basis using a paper or a computer-based system. The time-records have to be authorised by the project manager or other superior.”
Timesheets are a key element to EU projects, as it is the only way to justify personnel costs to the European Commission. Without the timesheets, CERN cannot obtain the reimbursement of personnel costs, nor justify the effort spent on the project.